Novel processes and compositions for electroplating nickel

ABSTRACT

IN ACCORDANCE WITH CERTAIN OF ITS ASPECTS, THIS INVENTION RELATES TO NOVEL COMPOSITIONS AND TO AN IMPLROVED PROCESS FOR ELECTROPLATING BRIGHT NICKEL WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS NICKEL-CONTAINING ELECTROPLATING BATH WHICH CONTAINS (A) A FIRST PRIMARY BRIGHTENER, (B) A SECONDARY BRIGHTENER, AND (C) AS AN ADDITIONAL COOPERATING PRIMARY BRIGHTENER, A NITROGEN-HETEROCYCLIC COMPOUND OF THE FORMULA:   (A-(RING(-R*)A)-(R)B-)X-RING(-R*)A-A WHERE A IS ATTACHED   TO N   WHEREIN EACH   RING   IS INDEPENDENTLY A PYRIDINE, QUINOOLINE OR ISOQUINOLINE NUCLEUS; EACH A IS AN INTEGER 0-6; EACH A IS INDEPENDENTLY OXYGEN (O) OR THE GROUP -OR&#39;&#39;SO3M WHEREIN R&#39;&#39; IS A DIVALENT HYDROCARBON GROUP OF 1-12 CARBON ATOMS AND M IS HYDROGEN, A NITROGEN ATOM, OR A BATH-COMPATIBLE METAL CATION; R IS A DIVALENT GROUP CONTAINING 1-12 CARBON ATOMS; B AND X ARE INTEGERS 0-1; A IS   -OR&#39;&#39;SO3M   WHEN X=0; AND R* IS A SUBSTITUENT SELECTED FROM THE GROUP CONSISTING OF ALKYL, HYDROXYALKYL, HALOGEN, ALKOXY, CARBOXYL, CARBALKOXY, ACETYL, SULFO, CARBOXAMIDE, CYANO, ARALKYL, ALKARYL, AND ARYL; ALL UNSUBSTITUTED CARBON ATOMS ARE BONDED TO HYDROGEN ATOMS; AND WHEN X=0 AND A IS - OR&#39;&#39;SO3M, (D) A SECONDARY AUXILIARY BRIGHTENER.

Patented July 13, 1971 3,592,943 NOVEL PROCESSES AND COMPOSITIONS FOR ELECTROPLATING NICKEL Frank Passal, Detroit, Mich., assignor to M & T Chemicals Inc., New York, N.Y. N Drawing. Filed Oct. 25, 1967, Ser. No. 677,864

Int. Cl. C23b /08 US. Cl. 204-49 16 Claims ABSTRACT OF THE DISCLOSURE wherein each is independently a pyridine, quinooline or isoquinoline nucleus; each a is an integer 0-6; each A is independently oxygen (0) or the group -OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; R is a divalent group containing 1-12 carbon atoms; b and x are integers 0-1; A is when x=0; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamide, cyano, aralkyl, alkaryl, and aryl; all unsubstituted carbon atoms are bonded to hydrogen atoms; and, when x=0 and A is ORSO M, (d) a secondary auxiliary brightener.

This invention relates to a process for nickel plating and to compositions useful for nickel plating. More particularly, it relates to processes and compositions for bright nickel plating.

It is an object of this invention to provide processes and compositions for nickel plating including bright nickel alloy plating. A particular object of this invention is to provide processes and compositions which may be used to provide improved bright nickel plated articles. A further object of this invention is to provide an improved process for the electrodeposition of bright and smooth nickel deposits including nickel-alloy deposits. Other objects will be apparent to those skilled-in-the-art on inspection of the following description.

In accordance with certain of its aspects, this invention relates to novel compositions and to an improved process for electroplating bright nickel which comprises electrodepositing nickel from an aqueous nickel-containing electroplating bath which contains (a) a first primary brightener, (b) a secondary brightener, and (c) as an additional cooperating primary brightener, a nitrogen-heterocyclic compound of the formula:

J is independently a pyridine, quinoline, or isoquinoline nucleus; each a is an integer 0-6: each A is independently oxygen (0) or the group -ORSO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; R is a divalent group containing 1-12 carbon atoms; b and x are integers 0-1; A is ORSO M when x=0; and R* is a substituent selected from the group consisting of alkyl, hydroxalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamide, cyano, aralkyl, alkaryl, and aryl; all unsubstituted carbon atoms are bonded to hydrogen atoms; and, when x=0 and A is ORSO M, (d) a secondary auxiliary brightener.

Addition agents useful as brighteners in nickel plating baths may be divided into two classes (designated primary and secondary brighteners) on the basis of their predominate function.

Primary brighteners are materials used in low or relatively low concentrations, typically 0.00-20.2 g./l., which by themselves may or may not produce visible brightening action. Those primary brighteners which may exhibit some brightening effects when used alone generally also produce deleterious side-effects such as reduced cathode efiiciency, poor deposit color, deposit brittleness and exfoliation, very narrow bright plate range, or failure to plate at all on low current density areas.

Secondary brighteners may be materials which are ordinarily used in combination with primary brighteners but in appreciably higher concentrations than those of the primary brighteners, typically 1 g./l. g./l. These secondary brighteners may be aromatic sulfonates, sulfonamides or sulfimides (wherein the sulfur atom is bonded directly to the aromatic nucleus) which compounds may be used singly or in combination. These materials, themselves, may produce some brightening or grainrefining effects, but the deposits are not usually mirrorbright and the rate of brightening is usually inadequate.

Ideally, when primary and secondary brighteners of properly chosen and compatible nature are combined it is possible to obtain, over a wide current density range, ductile, leveled deposits which exhibit a good rate of brightening. The rate of brightening and leveling may vary in degree depending on the particular additives chosen and their actual and relative concentrations. A high degree of rate of brightening and leveling is generally desirable, particularly where maximum luster is desired with minimum nickel thicknesses. The concentrations of the secondary brighteners may usually vary within fairly wide limits. The concentrations of the primary brighteners must usually be maintained within fairly narrow limits in order to maintain desirable properties including good ductility, adequate coverage over low current density areas, etc. Any bright nickel system which can be rendered more tolerant to fluctuations in primary brightener concentrations will have obvious advantages, particularly since the low concentration of primary brighteners and the intrinsic chemical nature of some make strict control by chemical wherein each 3 analysis difficult. A primary brightener which can be used over a wide range of concentration is of great value in bright nickel plating.

Secondary auxiliary brighteners may function to augment and improve the desirable characteristics (i.e. rates of brightening and leveling) imparted by primary and secondary brighteners. Such secondary auxiliary brighteners, which typically may be present in amount of 2 g./l.-30 g./l., preferably 2 g./l.l g./l., say 4 g./l., may include unsaturated hydrocarbon sulfonates such as sodium 3-chloro-2-butene sulfonate; sodium Z- ropene-lsulfonate; sodium l-phenylethene-2-sulfonate; sodium 3- methyl-l-butene-3-ol-l-sulfonate; sodium 3-hydroxy-l propene-l-sulfonate; etc.

The basis metals which may be electroplated in accordance with the process of this invention may include copper or copper alloys; ferrous metals including steel, iron, etc.; zinc and its alloys including zinc-base die castings; nickel, etc.

The basis metal may also bear a plate of copper and of semi-bright nickel before being subjected to the process of this invention. As used herein, the term bright nickel plate is meant to include bright alloy plates containing nickel as well as other metals (i.e. cobalt, iron, cobaltiron, etc.). Thus, alloy deposits containing nickel (such as bright nickel-cobalt deposits) maybe obtained according to the process of this invention.

The primary brighteners of the present invention may be useful with e.g. Watts type baths, high chloride type baths, and sulfamate type baths, including those typified by the illustrative baths of Tables I, II, and III.

TABLE I Watts-type baths Nickel sulfate200 to 400 g./l.

Nickel chloride-30 to 75 g./l.

Boric acid30 to 50 g./l.

Temperature-30 C. to 65 C.

pH3.5 to 5.0 electrometric.

With agitation (either mechanical, air, or solution circulation by pumping).

TABLE H High chloride baths Nickel chloridel50 to 300 g./l.

Nickel sulfate40 to 225 g./1.

Boric acid-30 to 50 g./l.

Temperature30 C. to 65 C.

pH3.5 to 5.0 electrometric.

With agitation (either mechanical, air, or solution circulation by pumping).

TABLE III Sulfamate-type baths Nickel sulfamate330 to 600 g./l.

Nickel chloride-l to 60 g./l.

Boric acid-35 to 55 g./l.

Temperature30 C. to 55 C.

pH3.5 to 5.0 electrometric.

With agitation (either mechanical, air, or solution circulation by pumping).

Other nickel plating baths may include those containing, as a source of nickel, nickel fiuoborate with nickel chloride. In the above tables, the nickel chloride is given as the hexahydrate NiCl .6H O, and the nickel sulfate as the heptahydrate NiSO .7H O. Other compounds e.g. Igoric acid and nickel sulfamate are given on an anhydrous asls.

The plating conditions for electrodeposition from the aforementioned baths may for example include temperature of 30 C..65 C., pH of 3.5-5 electrometric, and preferably 3.8-4.5, cathode current density of 1-10 amps. per sq. dm. Typical preferred current density of the baths of 4 Table I may be 4-6 amps. per sq. dm. Agitation may be preferred while plating.

It is a particular feature of the process of this invention that it permits outstanding results when a Wattstype bath is employed.

The first primary brightener which may be employed in the practice of this invention may include water-soluble quaternized nitrogen heterocyclic compounds.

Thus, the first primary brightener which may be employed in practice of this invention may include nitrogen heterocyclic compounds having as cation (1) Rm N+ (I) wherein is a pyridine, quinoline, or isoquinoline nucleus (including such nuclei when substituted or unsubstituted); m is 0-5; Z is CX=CHX; X is an active halogen group such as chloro or bromo; R" is a substituent selected from the group consisting of alkyl preferably having l4 carbon atoms, hydroxyalkyl preferably having l-4 carbon atoms, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, benzyl, sulfo, carboxamido, and cyano.

More particularly, the first primary brightener may be a compound (II) wherein X is a bath-soluble, bath-compatible anion, typically bromide, chloride, iodide, fluoride, acetate sulfate, methosulfate, ethosulfate, citrate, chloroacetate, perchlorate, etc. and Z is CX=CHX wherein X is an active halogen such as chloro or bromo and preferably X may be a halogen such as chloride or bromide. These compounds may be conveniently prepared by the reaction:

e.g. the reaction of pyridine and 1,2,3-trichloropropene to form N-2,3-dichloropropenyl pyridinium chloride. When Z is CX=CHX and, when X is bromo, then compound II will preferably be prepared by the reaction of an acetylenic compound III X" (II) wherein Z is -CX=CHX and X is an active halogen group such as chloro or bromo. Quaternized first primary brighteners may include:

N QI/ wherein Q is 2,3-dichloropropenyl or 2,3-dibromopropenyl and X is a halide (chloride or bromide).

According to one aspect of the invention, it is preferred that R" (in Formula II) be alkyl or hydroxyalkyl, and m be an integer -5. When m is 2-5, there may be both alkyl and hydroxyalkyl groups on the molecule. R" may typically be methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-amyl, n-hexyl, n-octyl, 2-ethylhexyl, etc., hydroxymethyl, beta-hydroxyethyl, gamma-hydroxypropyl, beta-dihydroxypropyl, etc.

Typical compounds which may fall within the scope of the starting materials represented by Formula III may be:

TABLE IV 2,6dimethyl N-propargyl pyridinium bromide 3,5-dimethyl N-propargyl pyridinium bromide 2,4-dimethyl N-propargyl pyridinium bromide 3,4-dimethyl N-propargyl pyridinium bromide 2,5-dimethyl N-propargyl pyridinium bromide 3-ethyl-4-methyl N-propargyl pyridinium bromide 2,4,6-trimethyl N-propargyl pyridinium bromide 2-beta-hydroxyethyl N-propargyl pyridinium bromide 2-gamma-hydroxypropyl N-propargyl pyridinium bromide 3-hydroxymethyl N-propargyl pyridinium bromide 2-methyl-6-gamma-hydroxypropyl N-propargyl pyridinium bromide 2-ethyl 4,6-di-beta-hydroxyethyl N-propargyl pyridinium bromide 2,4,6-tri-hydroxymethyl N-propargyl pyridinium bromide The preferred starting materials which may be used to prepare the first primary brighteners (where in X is bromide in Formula HI) may include 2,4,6-trimethyl N- propargyl pyridinium bromide.

In Formula II above when Z is CX=CHX, the compound may be rum- N+ In this embodiment, it is preferred that X be an active halogen i.e. bromo or chloro, and that m be 0.-3. These compounds may include N-2,3-dihalopropenyl pyridinium halide.

Typical first primary brightener compounds which may fall within the scope of Formula II may include:

TABLE V N-2,3-dibromopropenyl 2,4,6-trimethylpyridinium bromide N-2,3-dibromopropenyl 3,5-dimethylpyridinium bromide N-2,3-dibromopropenyl 4-isopropylpyridinium bromide N-2,3-dibromopropenyl 2,6-dimethylpyridinium bromide N-2,3-dibromopropenyl Z-aminopyridinium bromide N-2,3-dibromopropenyl 3-methylpyridinium bromide N2,3-dibromopropenyl 3-cyanopyridinium bromide N-2,3-dibromopropenyl 4-ethylpyridinium bromide N-2,3-dibromopropenyl 4-methylpyridinium bromide N-2,3-dibromopropenyl 2,4-dimethylpyridinium bromide N-2,3-dibromopropenyl 2-chloropyridinium bromide N-2,3-dibromopropenyl Z-ethylpyridinium bromide N-2,3-dibromopropenyl 2-beta-hydroxyethylpyridinium bromide N-2,3-dibromopropenyl Z-gamma-hydroxypropylpyridinium bromide N-2,3-dibromopropenyl 2-methylquinolinium bromide N-2,3-dibromopropenyl 2-p-methoxybenzylaminopyridinium bromide N-2,3-dibromopropenyl isoquinolinium bromide N-2,3-dibromopropenyl 3-sulfopyridinium bromide (Na salt) N-2,3-dibromopropenyl 3-hydroxymethylpyridinium bromide N-2,3-dibromopropenyl Z-methylpyridinium bromide N-2,3-dibromopropenyl 3,4-dimethylpyridinium bromide N-2,3-dibromopropenyl 2,5-dimethylpyridinium bromide N-2,3-dibromopropenyl 3-ethyl-4methylpyridinium bromide N-2,3-dibromopropenyl 4-methylquinolinium bromide N-2,3-dibromopropenyl 2-aldoximopyridinium bromide N-2,3-dibromopropenyl 2,6-diaminopyridinium bromide N-2,3-dichloropropenyl pyridinium chloride N-2,3-dichloropropenyl pyridinium iodide N-2,3-dichloropropenyl 3,4-dimethylpyridinium iodide N-2,3-dichloropropenyl 4-methylpyridinium iodide N-2,3-dichloropropenyl Z-methylpyridinium iodide bis-N,N'-2,3 dichloropropenyl-4,4'-dipyridinium dichloride bis-N,N'-2,3 dibromopropenyl-4,4-dipyridinium dibromide The first primary brightener may be present in the bath in effective amount of 0.002 g./l.-0.075 g./l., preferably 0.005 g./l.-0.03 g./l, say 0.01 g./l.

The preferred nickel electroplating baths of this invention may include secondary brighteners, present in typical amounts of 1 g./1. g./1., preferably 1 g./l.-2O g./l., such as the sulfo-oxygen compounds typical of which may be saccharin, and sodium benzene monosulfonate. The latter secondary brightener may be preferred when zinc-tolerance is desired because of its ability to tolerate higher concentrations of zinc as contaminant without giving striations in the low current density areas. In high chloride baths, it may be preferred to use saccharin or the sodium salt of sulfonated dibenzothiophene dioxide. Naphthalene sulfonates may be found to have little or no effectiveness in the process of this invention. Other secondary brighteners may include sodium m-benzene disulfonate and dibenzene disulfonimide having the respective formulas SO Na and The additional cooperating primary brightener may be a nitrogen heterocyclic compound of the formula:

Mi i

1 A- LB 1 wherein each and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

When A represents the group ORSO M, M may be a bath-compatible metal cation such as sodium, potassium, lithium, magnesium, cobalt, nickel, ammonium, etc. When M is a nitrogen atom, the nitrogen atom is preferably a part of the molecule so that an inner salt may be formed. When M is a nitrogen atom which is a part of a heterocyclic ring of the molecule the resulting inner salt (sulfobetaine) may be prepared by the direct reaction of a sultone and an N-oxide compound, preferably in molten state. When M is hydrogen, the corresponding acid may be formed.

Examples of various sub-classes of cooperating primary brighteners include the following:

( H z)x wherein A is selected from the group consisting of the oxygen atom, and a group of the formula OR'SO M wherein R is a divalent hydrocarbon group of 1-12 atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer -4; k is an integer 08; all unsubstituttd carbon atoms are bonded to hydrogen atoms, and R** is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

and

wherein each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

wherein each a is an integer 0-4; k is an integer 0-8; R* is a substituent selected from the group consisting of alk l, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and

aryl; all unsubstituted carbon atoms are bonded to hydrogen atoms.

wherein R is a divalent hydrocarbon group of 1-12 caratoms and M is hydrogen, a nitrogen atom, or a bathcornpatible metal cation; each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl. In this formula, one

group may be replaced by an oxygen atom (designated O) covalently bonded to one hetero-nitrogen atom.

wherein R is a divalent hydrocarbon group of 1-12 carbon atoms; M is hydrogen, a nitrogen atom, or a bathcompatible metal cation; a is an integer 0-5; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

wherein R is a divalent hydrocarbon group of 112 carbon atoms; each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

As can be seen from the foregoing formulas, a represents the number of substituents bonded to the nitrogen heterocyclic rings. When is quinoline, a may be an integer greater than 5, but is preferably an integer 0-5.

Specific examples of such compounds include the following:

1 1 1 l l 1,6-di-4-pyridylhexane di-N-oxide;

pyridyloxypropanesulfobetaine;

4-methyl pyridyloxypropanesulfobetaine;

2,6-dimethyl pyridyloxypropanesulfobetaine;

2-methyl pyridyloxypropanesulfobetaine;

4,4-dipyridinium-bis (oxypropanesulfobetaine) 4 (4'-pyridinium N-oxide)-pyridinium oxypropanesulfobetaine;

3-methyl pyridine oxypropanesulfobetaine;

4 (-4 methylene pyridinium N-oxide)-pyridinium oxypropanesulfobetaine;

4,4-di-pyridinium methylene bis (oxypropanesulfobetaine);

4,4'-di-pyridinium ethylene bis(oxypropanesulfobetaine);

4- 4'-ethylene pyridinium N-oxide)-pyridinium oxypropanesulfobetaine;

4,4-di-pyridinium bis (oxybutanesulfobetaine) 4--(4-ethy1ene pyridinium N-oXide)-pyridinium oxybutanesulfobetaine;

4-(4'-propy1ene pyridinium N-oXide)-pyridinium oxypentanesulfobetaine;

di-pyridinium propylene bis(oxypentanesulfobetaine).

In addition, it is to be understood that the acid forms and the bath-compatible metal salts of the named sulfobetaine compounds may also be employed. Typical examples of such compounds may include:

sodium salt of pyridyloxypropanesulfobetaine acid form of pyridyloxypropanesulfobetaine potassium salt of pyridyloxypropanesulfobetaine magnesium salt of pyridyloxypropanesulfobetaine nickel salt of pyridyloxypropanesulfobetaine sodium of 4-methyl pyridyloxypropanesulfobetaine acid form of pyridyloxypropanesulfobetaine potassium salt of 4-methyl pyridyloxypropanesulfobetaine magnesium salt of 4-methyl pyridyloxypropanesulfobetaine nickel salt of 4-methyl pyridyloxypropanesulfobetaine sodium salt of 2,6-dimethyl pyridyloxypropanesulfobetaine acid form of 2,6-dimethyl pyridyloxypropanesulfobetaine potassium salt of 2,6-dimethyl pyridyloxypropanesulfobetaine magnesium salt of 2,6-dimethyl pyridyloxypropanesulfobetaine nickel salt of 2, 6-dimethyl pyridyloxypropanesulfobetaine ammonium salt of 2,6-dimethyl pyridyloxypropanesnlfobetaine sodium salt of Z-methyl pyridyloxypropanesulfobetaine acid form of 2-methy1 pyridyloxypropanesulfobetaine potassium salt of 2-methyl pyridyloxypropanesulfobetaine magnesium salt of Z-methyl pyridyloxypropanesulfm betaine nickel salt of Z-methyl pyridyloxypropanesulfobetaine sodium salt of 4,4'-dipyridinium-bis (oxypropanesulfobetaine) acid form of 4,4'-dipyridinium-bis (oxypropanesulfobetaine) potassium salt of 4,4'-dipyridinium-bis(oxypropanesulfobetaine) magnesium salt of 4,4-dipyridinium-bis(oxypropanesulfobetaine) nickel salt of 4,4-dipyridinium-bis(oxypropanesulfobetaine) sodium salt of 4-(4'-pyridinium N-oxide)-pyridiniumoxypropanesulfobetaine acid form of 4-(4-pyridinium N-oXide)-pyridiniumoxypropanesulfobetaine potassium salt of 4-(4'-pyridinium N-oxide)-pyridiniumoxypropanesulfobetaine magnesium salt of 4-(4pyridinium N-oXide)-pyridiniumoxypropanesulfobetaine nickel salt of 4-(4-pyridinium N-oXide)-pyridiniumoxypropanesulfobetaine sodium salt of 3-methyl pyridine oxypropanesulfobetaine acid form of B-methyl pyridine oxypropanesulfobetaine potassium salt of 3-methyl pyridine oxypropanesulfobetaine magnesium salt 3-methyl pyridine oxypropanesulfobetaine nickel salt of B-methyl pyridine oxypropanesulfobetaine sodium salt of 4-(4-methylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine acid form of 4-(4'-methylene pyridinium N-oXide)- pyridinium oxypropanesulfobetaine potassium salt of 4-(4-methylene pyridinium N-oXide)- pyridinium oxypropanesulfobetaine magnesium salt of 4-(4-methylene pyridinium N-oXide)- pyridinium oxypropanesulfobetaine nickel salt of 4-(4-methylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine sodium salt of di-pyridinium propylene bis(oxypentanesulfobetaine) acid form of di-pyridinium propylene bis(oxypentanesulfobetaine) potassium salt of di-pyridinium propylene bis(oxypen- I tanesulfobetaine) magnesium salt of di-pyridinium propylene bis(oxypentanesulfobetaine) nickel salt of di-pyridinium propylene bis(oxypentanesulfobetaine) ammonium salt of di-pyridinium propylene bis(0Xypentanesulfobetaine) sodium salt of 4,4'-dipyridinium methylene bis (oxypropanesulfobetaine) acid form of 4,4'-dipyridinium methylene bis(oxypropanesulfobetaine) potassium salt of 4,4'-dipyridinium methylene bis(oxypropanesulfobetaine) magnesium salt of 4,4'-dipyridinium methylene bis(oXypropanesulfobetaine) nickel salt of 4,4'-dipyridinium methylene bis(oxypropanesulfobetaine) sodium salt of 4,4-di-pyridinium ethylene bis(oXypropanesulfobetaine) acid form of 4,4-di-pyridinium ethylene bis(oxypropanesulfobetaine) potassium salt of 4,4'-di-pyridinium ethylene bis(oxypropanesulfobetaine) magnesium salt of 4,4'-di-pyridinium ethylene bis(oXypropanesulfobetaine) nickel salt of 4,4'-di-pyridinium ethylene bis(0Xypropanesulfobetaine) sodium salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine acid form of 4-(4'-ethylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine potassium salt of 4-(4'-ethylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine magnesium salt of 4-(4'-ethylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine nickel salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxypropanesulfobetaine sodium salt of 4,4'-di-pyridinium bis(oxybutanesulfobetaine) acid form of 4,4'-di-pyridinium bis(oxybutanesulfobetaine) potassium salt of 4,4'-di-pyridinium bis(oxybutanesulfobetaine) magnesium salt of 4,4-di-pyridinium bis(oxybutanesulfobetaine) nickel salt of 4,4'-di-pyridinium bis(oxybutanesulfobetaine) sodium salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxybutanesulfobetaine acid form of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxybutanesulfobetaine potassium salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxybutanesulfobetaine magnesium salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxybutanesulfobetaine nickel salt of 4-(4-ethylene pyridinium N-oxide)- pyridinium oxybutanesulfobetaine sodium salt of 4-(4'-propylene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine acid form of 4-(4'-propylene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine potassium salt of 4-(4-propylene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine magnesium salt of 4-(4'-propylene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine nickel salt of 4-(4-propylene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine ammonium salt of 4-(4'-propy1ene pyridinium N-oxide)- pyridinium oxypentanesulfobetaine The sultones which may be employed to prepare the novel brighteners of this invention may include those containing a carbon-oxygen-sulfur-carbon linkage in a ring, the hexavalent sulfur atom being further bonded to two additional oxygen atoms, and may be represented by the general formula SOz-O wherein R is a hydrocarbon-di-yl moiety which contains at least 3 carbon atoms. The sultone which may preferably be used may contain 35 carbon atoms, these sultones being characterized by generation of a minimum of foaming, particularly with strong solution agitation. The most preferred sultone may be 1,3-propane sultone,

We CH2 although sultones such as 1,1,3-trimethyl propane sultone,

(3H3 GHQ-04:11;

CHaCH 0 so, 1,4-butane sultone,

on, (2H 11, OH; 0

and 1,3- butane sultone,

(|3H (j3HCH1 CH2 0 S02 also may produce highly useful additives. The longer chain alkane sultones or other sultones containing more than 5 carbon atoms, such as tolyl sultone,

may be also used to produce additives within the scope of the invention. Typical reaction products of such sultones with pyridine oxide may include:

N l o in/b i wherein R*, R, R, M, a, b and x are as previously defined.

For example, a method of preparing the compound comprises reacting a compound of the Formula 1 13 with an oxidizing agent to produce a compound of the Formula 2 I (an and reacting compound 2 with a sultone.

In the above formulas, p is an integer -1; Q is oxygen when p is 1 and N is trivalent when p is 0; each is independently a pyridine, quinoline or isoquinoline nucleus; each a is an integer 05; each A is independently oxygen (0) or the group OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; R is a divalent group containing 1-12 carbon atoms; 12 is an integer 0-1; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

The additional cooperating primary brightener compounds of the invention may be prepared by the condensation of a suitable nitrogen heterocyclic compound with an alkyl halide and/or another nitrogen heterocyclic compound in the presence of a Friedel-Crafts catalyst to obtain a dipyridyl compound. The resulting dipyridyl compound may then be reacted with hydrogen peroxide, an organic peracid, or other oxidizing agent to produce the corresponding monoand/ or di-N-oxide compounds. The N-oxide compounds may then be reacted with one or more of the sultone compounds to produce the corresponding oxysulfoalkyl N-heterocyclic compounds. In these reactions stoichiometric amounts of reactants may be employed. For example, 2 moles of propane sultone may be reacted with approximately 1 mole of 4-4'-dipyridyl propane di-N-oxide to produce the corresponding di-oxysulfoalkyl compound, whereas only one mole of propane sultone may be reacted with 1 mole of 4-4-dipyridyl propane di- -oxide to produce a compound containing an N-oxide group and an oxysulfoalkyl group within the molecule.

Examples of specific compounds which may be prepared may include the following:

O CHzCH C HgS O Na 14 0.05 g./l., preferably 0.001 g./l.0.03 g./l., say 0.002 0.02 g./l.

Other additives which may be used include anti-pitting agents which may be exemplified by sodium lauryl sulfate and sodium di-N-hexylsulfosuccinate.

Plating of nickel by the novel process of this invention permits attainment of a brilliant, ductile, highly leveled deposit of bright nickel over a Wide range of current density.

:For purpose of providing those skilled-in-the-art with a better understanding of this invention, the following examples are set forth wherein all parts are parts by weight unless otherwise specified.

In these examples, the Watts Bath contained:

G./1. NiSO -7H O 300 NiCl -6H O 60 Boric acid 45 The high chloride bath contained:

NiSO -7H O 225 NiCl -6H O 225 Boric acid 45 The sulfamate bath contained:

Nickel sulfamate 375 NiCl -6H O 4S Boric acid 45 The first primary brighteners used were:

(A') -N-2,3-dichloropropenyl pyridinium chloride (B') N 2,3 dibromopropenyl-2,4,6-trimethyl pyridinium bromide (C') N,N'bis-2,3-dichloropropenyl-4,4'-dipyridinium dichloride (D) 'N,N'bis 2,3 dibromopropenyl-4,4'-dipyridinium dichloride The secondary brighteners used were:

(A) Sacchan'n (Na salt) (B") Sodium benzene monosulfonate (C") Disodium m-benzene disulfonate D") Dibenzene sulfonimide (E") Sulfonated dibenzothiophene dioxide (Na salt) The secondary auxiliary brighteners used were: (A"') Sodium 3-chloro-2-butene sulfonate (B") Sodium 2-propene-l-sulfonate (C") Sodium 1-phenylethene-2-sulfonate The anti-pitting agents used were:

(A") Sodium lauryl sulfate (B"") Sodium di-N-hexyl-sulfosuccinate The additional cooperating primary brighteners used were:

(A) 4,4 dipyridyl (B) 1,3-di-4-pyridylpropane (C) 1,5-di-4-pyridylpentane (D) 4,4'-dipyridyl di-N-oxide (E) 1,3-di-4-pyridylpropane di-N-oxide (F) 1,5-di-4-pyridylpentane-di-N-0xide (G) 1,3 di 4 pyridylpropane dioxypropanesulfobetaine (H) 1,5 di 4-pyridylpentane dioxypropanesulfobetaine (I) pyridyloxypropanesulfobetaine (J) Z-methylpyridyloxypropanesulfobetaine (K) 4-methylpyridyloxypropanesulfobetaine (L) 2,6-dimethylpyridyloxypropanesulfobetaine (M) 3-methylpyridyloxypropanesulfobetaine (N) 4,4-dipyridyldioxypropanesulfobetaine Brilliant, ductile, highly leveled deposits with compressive internal stress were obtained in all cases where the word Good is used in the Results column. Non-uniformly hazy or milky deposits with good ductility but poor leveling for certain examples are indicated in the Results column by the Word Poor. The type of deposit desired for the purposes of this invention are of the appearance and physical properties indicated as Good.

Amount, Example No. Additives g./l. Results I 1 $3 'g g }Poor O. 002 3 "{A 3. 2 i

A 0. 010 3 B O. 002 Good 0. 010 I 4 1% I1 DOT 5 "{BD h l n DO- A' 0. 010 6 B 0. 002 Good 0. 010 8 a ll D0- 0 0. 004 9 B 0. 010 Good.

A 3. 2 A O. 010 B 0. 002 D0. 10 BI! 3. 0 D 2. 0 C 0. 004 ll A 0. 010 D0.

B 7. 5 12 {u '39; }Poor E 0. 002 13 A 0. 010 Good.

A 3. 2 14 :2 }P0or.

F 0. 002 15 A 0.010 Good A" 3. 2 16 "i2" }P0or G 0. 002 17 A 0. 010 Good A 3. 2 18 "{EI! '2 }Poor H 0. 003 19 A 0. 010 Good A" 3. 2 I 0. 020 20 A 3. 2 Pool.

A 3. 2 I I 0.020 21 2 'g g Good A 3: 2 K 0. 020 22. 3. 2 Poor.

A 3. 2 K 0. 020 23 in 2 3 Good.

A 312 L 0. 020 24 {A 3. 2 Poor.

A 3. 2 L 0.020 25 in Good.

A 3. 2 J 0. 020 26 A 3. 2 Poor.

A 3. 2 J I 0. 020 27 in gig Good A 3. 2 M 0. 020 28 A 3. 2 Poor.

A 3. 2 M 0. 020 29 A 0. 010 Good A" 3. 2 A 3. 2 A 0. 010 30 g!!! DO- A 3. 2 A 0. 010 31 g!!! 0' D0;

A 3. 2 B 0. 010 32 B 0. 002 D0.

C" 10. 0 C 0. 005 33 C 0. 004 DO.

A 3. 2 D 0. 005 34 G 0. 002 DO.

A 3. 2 A 0. 010 35 B 0. 002 D0.

Amount, Example No. Additives g./l. Results A 0.010 as g Do 13' 2.8 A 0. 010 37 g Do.

13 21s A 0. 010 as -.g,, 2 3 Do.

A 312 A 0. 010 30 2,, 'gg D0.

8 215 o 0. 0075 40 2., g Do.

A 312 D 00075 41 "2., 3 Do.

A 312 A 0. 010 42 5 Do.

B 2.0 A 0. 010 44 N 0. 004 Do.

The following Examples Nos. 45-48 inclusive illustrate the improved results which may be obtained using the compositions of the invention in a nickel-cobalt alloy bath of the following composition:

pH3.8 electrometric Temperature60 C.

Percent by weight cobalt in deposit50 Other nickel-cobalt alloy baths may also be employed with good results.

Amount Example No. Additives g./l. Results A 0.010 45 B 0.002 Good 3.2 A 0.010 46 5g. 39;} DO.

3.2 a 222 47 Do.

A 3.2 0.010 48 -g g Do.

As can be seen from the foregoing, examples in the following groups show the beneficial effects which may result from combining a first primary brightener and an additional cooperating primary brightener in accordance with the invention without the use of a secondary auxiliary brightener:

The examples grouped as follows demonstrate the improved results which may be obtained by the use of an additional cooperating primary brightener in a system which contains a first primary brightener, a secondary brightener, and a second auxiliary brightener:

Groups of examples:

Example 49 Preparation of Compound D 4,4 dipyridyl di-N-oxide) A mixture of 15.6 grams of 4,4-dipyridyl (Compound A), 40 grams of hydrogen peroxide (30 percent by weight), 35 milliliters of glacial acetic acid, and 75 milliliters of water may be heated under reflux conditions with stirring. The liquids are then removed by heating under vacuum and the resulting yellow product washed with acetone to yield 21 grams of crystalline 4,4'-dipyridyl di- N-oxide product decomposing at 160 C.

Example 50 Preparation of Compound E (1,3-di-4-pyridylpropane di-N-oxide) To a solution of 40 grams of 1,3-di-4-pyridylpropane in 70 milliliters of glacial acetic acid and 150 milliliters of water may be added 80 grams of hydrogen peroxide (30 percent by weight) and the resulting mixture may be refluxed, concentrated in vacuo on a steam bath, and acetone added to yield a crystalline mass which may be filtered. The crystals may be washed with acetone to yield 30 grams of 1,3-di-4-pyridylpropane di-N-oxide with a melting point of 248250 C.

Example 51 Compound F (1,5-di-4-pyridylpentane-di-N-oxide) may be prepared by combining 2.26 grams of 1,5-dipyridylpentane With 4 milliliters of 30% hydrogen peroxide in 4 milliliters of glacial acetic acid and 8 milliliters of water. The mixture may be heated on a steam bath, evaporated to dryness, the residue taken up with acetone and chilled to produce crystals. The crystals may be separated by filtration and dried to yield 1.7 grams of 1,5-di-4-pyridylpentane-di-N-oxide (melting point 210-215 C. with decomposition) Example 52 Compound G 1,3-di-4-pyridylpropane dioxypropanesulfobetaine To a methanol solution milliliters) containing 6 grams of Compound E from Example 50 may be added a methanol solution (25 milliliters) containing 7.5 grams of propane sultone. The mixture may be stirred at room temperature and then gently refluxed for one hour and cooled. Acetone may be added and the resulting crystals separated, Washed with acetone and air-dried to yield 10 grams of 1,3-di 4 pyridylpropane dioxypropanesulfobetaine (melting point 178-180 C., with decomposition).

Example 5 3 Compound H (1,5 di-4-pyridylpentane dioxypropanesulfobetaine) may be prepared by dissolving 1.5 grams of 1,5-di 4 pyridylpentane-di N oxide in 50 milliliters of methanol and adding 4 grams of propanesultone dissolved in 5 milliliters of methanol to form a reaction mixture. The reaction mixture may be heated and stirred and the methanol removed in vacuo on a steam bath to produce 1,5 di 4 pyridylpentane dioxypropanesulfobetaine as a light yellow oil which is soluble in isopropanol.

Example 54 Compound I (pyridyloxypropanesulfobetaine) may be prepared by dissolving 9.5 grams of pyridine-N-oxide in 30 milliliters of hot ethanol, heating to boiling under reflux, slowly adding 13 grams of propanesultone dissolved in 10 milliliters of ethanol and heating under reflux for an additional one hour. The product, after cooling the reaction mixture, may be filtered, washed with acetone and air-dried to yield 13.7 grams of pyridyloxypropanesulfobetaine having a melting point of 195 C.

Example 55 Compound I (Z-methylpyridyloxypropanesulfobetaine) may be prepared by adding 10.9 grams of 2-picoline-N- oxide dissolved in milliliters of acetone to a suitable reaction vessel equipped with a stirrer, reflux condenser, and means for addition of reactants. The solution may be heated to boiling and 12.2 grams of propane sultone in 50 milliliters of acetone may be added dropwise to the boiling mixture over a period of 15 minutes. A white precipitate may form and the resulting precipitate may be filtered and washed with acetone to yield 10.0 grams of cream colored 2 methylpyridyloxypropanesulfobetaine product having a melting point of 2082l2 C.

Example 56 Compound K (4-methylpyridyloxypropanesulfobetaine) may be prepared by reacting 10.9 grams of 4-picoline-N- oxide with 12.2 grams of propane sultone according to the same procedure used for compound I to yield 15.5 grams of 4-methylpyridyloxypropanesulfobetaine as a white powder having a melting point of 208209 C.

Example 57 Compound L (2,6 dimethylpyridyloxypropanesulfobetaine) may be prepared by reacting 12.3 grams of 2,6-lutidine-N-oxide and 12.2 grams of propane sultone accord ing to the same procedure used for Compound J to yield 4.7 grams of cream-colored solid 2,6-dimethylpyridyloxypropanesulfobetaine product having a melting point of ZOO-204 C.

Example 58 Compound M (3-methylpyridyloxypropanesulfobetaine) may be prepared by reacting 10.9 grams of 3-pico1ine-N- oxide and 12.2 grams of propane sultone according to the same procedure used for Compound I to yield 23.1 grams of solid cream-colored 3-methylpyridyloxypropanesulfobetaine product having a melting point of 162165 C.

1 9 Example 59 Preparation of compound N (4,4dipyridyldioxypropanesuliobetaino A sample of 4.7 grams of 4,4-dipyridyl-di-N-oxide from Example 49 may be dissolved in 500 milliliters of dimethyl formamide at 90 C. and 10 grams of propane sultone dissolved in 25 milliliters of dimethyl formamide may be added. The mixture may be stirred for two hours and the resulting yellow precipitate separated by filtration to yield 2.6 grams of yellow crystalline 4,4-dipyridyldioxypropanesulfobetaine having a melting point of 225 C. (decomposition).

In all of the above examples which fall within the scope of this invention, it was observed that the nickel plate was characterized by a high degree of leveling, ductility, and rate of brightening. The combination of primary brighteners gave extremely high leveling, ductility, rate of brightening, and substantial improvement in coverage in the low current density area. Improvement in coverage in the low current density areas may be particularly outstandmg.

It will be apparent to those skilled-in-the-art that various modifications may be made to the specific embodiments herein set forth by way of example.

I claim:

1. An improved process for electroplating bright nickel which comprises electrodepositing nickel from an aqueous nickel-containing electroplating bath which contains (a) a first primary brightener, (b) a secondary brightener, and (c) as an additional cooperating primary brightener, a nitrogen-heterocyclic compound of the formula:

is independently a pyridine, quinoline, or isoquinoline nucleus; each a is an integer -6; each A is independently oxygen (0), or the group OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; R is a divalent group containing 1-12 carbon atoms; 15 and x are integers 0-1; A is ORSO M when 1:0; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl; all unsubstituted carbon atoms are bonded to hydrogen atoms; and when x=0 and A is OR'SO M, (d) a secondary auxiliary brightener.

2. A process as claimed in claim 1 wherein the nitrogen-heterocyclic compound is of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula ORSO M wherein R is a divalent hydrocarbon group of 112 carbon atoms and M is hydrogen, a nitrogen atom, or a bathcompatible metal cation; each a is an integer 04; b is an integer O-l; R is a divalent group containing 1-12 carbon atoms; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

3. A process as claimed in claim 2 wherein the nitrogenheterocyclic compound is of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula -OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath compatible metal cation; each a is an integer 0-4; b is an integer 0-1; R is a divalent group containing 1-12 carbon atoms; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

4. A process as claimed in claim 2, wherein the nitrogen-heterocyclic compound is of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bathcompatible metal cation; each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyanoaralkyl, alkaryl, and aryl.

5. A process as claimed in claim 2, wherein the nitrogen heterocyclic compound is of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

6. A process as claimed in claim 2, wherein the nitrogen-heterocyclic compound is of the formula:

wherein each a is an integer 0-4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R" is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralalkyl, alkaryl, and aryl.

7. A process as claimed in claim 2, wherein the nitrogen heterocyclic compound is of the formula:

wherein each a is an integer -4; k is an integer 0-8; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

8. A process as claimed in claim 2, wherein the nitrogen he'terocyclic compound is of the formula:

wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 04; k is an integer 08; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

9. An aqueous bright nickel plating bath composition which contains (a) a first primary brightener, (b) a secondary brightener, and (c) as an additional cooperating primary brightener, a nitrogen-heterocyclic compound of the formula:

A L {J wherein each is independently a pyridine, quinoline, or isoquinoline nucleus; each a is an integer 06; each A is independently oxygen (0) or the group -O'RSO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; R is a divalent group containing 1-12 carbon atoms; b and x are integers 01; A is OR'SO M when x=0; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl; all unsubstituted carbon atoms are bonded to hydrogen atoms; and when x=0' and A is OR'SO M, (d) a secondary auxiliary brightener.

10. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener, and (c) as a cooperating primary brightener, a compound of the formula:

PM S N: A fj" wherein A is selected from the group consisting of the oxygen atom and a group of the formula OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 0-4; b is an integer 0-1; R is a divalent group containing 1-12 carbon atoms; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, and aryl.

11. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener, and (c) as a cooperating primary brightener, a compound of the formula:

Rx a

wherein A is selected from the group consisting of the oxygen atom and a group of the formula -ORSO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 0-4; b is an integer G l; R is a divalent group containing 1-12 carbon atoms; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

12. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener, and (c) as a cooperating primary brightener, a compound of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula ORSO M wherein R is a divalent hydrocarbon group of 112 car bon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 04; k is an integer 08; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

13. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener and (c) as a cooperating primary brightener, a compound of the formula:

wherein A is selected from the group consisting of the oxygen atom and a group of the formula OR'SO M wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bath-compatible metal cation; each a is an integer 04; k is an integer 08; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

14. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener, and (c) as a cooperating primary brightener, a compound of the formula:

wherein each a is an integer 0-4; k is an integer 08; all unsubstitued carbon atoms are bonded to hydrogen atoms; and R* is a substitutent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

15. An aqueous bright nickel plating bath composition which contains (a) a primary brightener, (b) a secondary brightener, and (c) as a cooperating primary brightener, a compound of the formula:

wherein each a is an integer 0-4; k is an integer 08; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substitutent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, sulfo, carboxamido, cyano, aralkyl, alkaryl, and aryl.

16. An aqueous bright nickel plating bath composition which contains (a) a primary brightening agent, (b) a secondary brightening agent, and (c) as a cooperating primary brightening agent, a compound of the formula:

wherein R is a divalent hydrocarbon group of 1-12 carbon atoms and M is hydrogen, a nitrogen atom, or a bathcompatible metal cation; each a is an integer 04; all unsubstituted carbon atoms are bonded to hydrogen atoms; and R* is a substituent selected from the group consisting of alkyl, hydroxyalkyl, halogen, alkoxy, carboxyl, carbalkoxy, acetyl, benzy1,'su1fo, carboxamido, aralkyl, alkaryl, cyano, and aryl.

References Cited UNITED STATES PATENTS 3,170,855 2/1965 Kroll 20449 3,190,820 6/1965 Todt 20449 3,190,821 6/1965 Todt 20449 3,218,244 11/1965 Passal et a1 20449 3,296,103 1/1967 Passal 20449 3,336,324 8/1967 Richter et a1. 20449X 3,361,754 1/1968 Passal et a1. 20449X 3,413,295 ll/1968 Passal et a1. 260-290 DANIEL E. WYMAN, Primary Examiner C. F. DEES, Assistant Examiner US. Cl. X.R. 204112 

